Small stones and those close to the corticomedullary junction can be difficult to reliably identify. Features include 7 :. Given that one of the commonest sites for a stone to become lodged is the vesicoureteric junction, some centers perform the study in the prone position to establish if the stone is retained within the intravesical component of the ureter or has already passed into the bladder itself. Dual-energy CT is a technique allowing the composition of the calculus to be determined, by assessing stone attenuation at two different kVp levels.
Each CT vendor has its own algorithms for the use of dual-energy CT for assessing stone composition. Dual-energy CT may be useful in detecting stones concealed by the opacification of the collecting system Dual-energy CT has also been shown to predict the success of extracorporeal shock wave lithotripsy Surgical intervention typically involves a retrograde ureteric stent with subsequent laser lithotripsy.
In acutely septic patients who would be unsuitable for an anesthetic or in those who would not be suitable for a retrograde stent, such as those with poor retrograde access or abnormal anatomy, a percutaneous nephrostomy PCN with an antegrade stent followed by laser lithotripsy is preferred. Extracorporeal shock wave lithotripsy ESWL is usually performed in large proximal calculi in patients unsuitable for invasive management.
Percutaneous nephrolithotomy PCNL is usually reserved for large calculi near the pelviureteric junction, especially staghorn calculi, which are unlikely to be removable via retrograde access. Small asymptomatic stones in the kidney can be safely ignored, and if patients maintain good states of hydration, the risk of recurrent symptoms can be dramatically reduced Struvite stones are usually large staghorn calculi and result from infection.
These stones need to be treated surgically and the entire stone removed, including small fragments, as otherwise, these residual fragments act as a reservoir for infection and recurrent stone formation.
Uric acid stones usually are the result of low urinary pH, and hydration and elevation of urinary pH to approximately 6 are usually sufficient note rendering the urine too alkali e. Cystine stones may be difficult to treat and are difficult to shatter with ESWL.
Hydration and alkalinisation are usually first-line therapy. The differential of renal calculi is essentially that of abdominal calcifications. On CT there is usually little confusion as not only is CT exquisitely sensitive in detecting stones, but their location can also be precisely noted.
If non-contrast CT is equivocal for the location of the calcification, then a repeat CT with urographic phase contrast is usually able to clarify. Thus the differential diagnosis is predominantly on plain radiograph, and to a lesser degree ultrasound:. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form. Check for errors and try again. Thank you for updating your details.
Log In. Sign Up. Become a Gold Supporter and see no ads. Log in Sign up. Articles Cases Courses Quiz. About Recent Edits Go ad-free. Edit article. View revision history Report problem with Article. Protease inhibitors are a new class of medication used to treat patients with HIV disease.
Indinavir sulfate Crixivan , a protease inhibitor, is widely used to treat patients with HIV infections. Urinary lithiasis has been associated with the use of Indinavir. As with other renal calculi, ureteral stents, hydration, analgesics, and antispasmodics have provided favorable outcomes.
Nonsteroidal-anti-inflammatory drugs NSAID should be avoided as they have been shown to result in deterioration of renal function. Hyperhydration and acidification of urine are usually successful. Crystalluria may be associated with dysuria and urinary frequency. Flank or back pain is associated with intrarenal sludging and the classic syndrome of renal colic. It is also believed that Crixivan stones may act as a nidus for heterogenous nucleation leading to the development of mixed urinary stones.
Surgical intervention may be required in some patients. In addition, a combined medical and surgical intervention may be necessary. Indinavir therapy averaged 5. All patients presented with microscopic hematuria. The median number of symptomatic urinary stone episodes after initiating Indinavir was 2 stones per patients. Radiographically, Indinavir stones are typically radiolucent.
Abdominal CT scan demonstrated hydronephrosis without calcifications. CT scan with contrast may demonstrate the presence of crixivan stones. These stones can cause high grade ureteral obstruction. The radiolucent-gelatinous nature of such stones makes lithotripsy a poor choice of treatment. Men are affected four times more often than women. However, the majority of patients who form uric acid calculi have no detectable abnormalities in uric acid metabolism.
Factors that may contribute or predispose to uric acid stone formation include acidic or strongly concentrated urine, excess urinary excretion of uric acid, distal small bowel disease or resection regional enteritis , ileostomies, myeloproliferative disorders being treated with chemotherapy and inadequate caloric or fluid intake.
Treatment is tailored toward increasing urine volume and urinary pH. Unlike most other renal calculi, existing uric acid stones can often be dissolved with either systemic or topical alkalinizing agents. Medical History Pathophysiological factors: anemia, neoplastic disorders, intoxication, cardiac infarction, irradiation and treatment with cytotoxic agents.
Metabolic abnormalities: primary gout, Lesch-Nyhan syndrome. Pharmacologic influence on the excretion of uric acid: uricosuric agents probenecid, sulfinpyrazone, salycilates , diuretics thiazide, furosemide and analgesics, vitamin C. Treatment In contrast to other types of stones, medical therapy is the mainstay of treatment and prophylaxis. Potassium citrate at a dose titrated to alkalinize the urine to a pH of will dissolve uric acid stones.
Uric acid-related nephrolithiasis. Teitel J. A side effect of protease inhibitors. Letter] CMAJ 9 : , Clayman RV. Crystalluria and urinary tract abnormalities associated with indinavir. Journal of Urology. Witte M. Tobon A. Gruenenfelder J. Goldfarb R. Cobum M. Anuria and acute renal failure resulting from indinavir sulfate induced nephrolithiasis.
Kopp JB. Miller KD. Mican JA. Feuerstein IM. Vaughan E. Baker C. Pannell LK. Falloon J. Crystalluria and urinary tract abnormalities associated with indinavir [see comments].
Bruce RG. Munch LC. Hoven AD. Extracorporeal shock wave lithotripsy is also effective for ureteral stones, with an upper size limit of approximately 1 cm. Unknown ovarian effects are the basis for a relative contraindication to the use of extracorporeal shock wave lithotripsy in women of child-bearing age who have middle or distal ureteral stones. Percutaneous nephrolithotomy remains a safe and reliable method of removing large renal and proximal ureteral stones.
Advances in ureteroscopic techniques now allow calculi that are not good candidates for extracorporeal shock wave lithotripsy or percutaneous nephrolithotomy to be treated virtually anywhere within the ureter or kidney. Requires spontaneous passage of fragments Less effective in patients with morbid obesity or hard stones.
Ureteral obstruction by stone fragments Perinephric hematoma. Invasive Commonly requires postoperative ureteral stent. May be difficult to clear fragments Commonly requires postoperative ureteral stent.
Bleeding Injury to collecting system Injury to adjacent structures. Already a member or subscriber? Log in. Interested in AAFP membership? Learn more. Portis completed a residency in urology at the University of Alberta, Edmonton, Canada. Address correspondence to Chandru P. Sundaram, M. Louis, MO Reprints are not available from the authors. Urinary lithiasis: etiology, diagnosis and medical management.
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Management of lower pole nephrolithiasis: a critical analysis. Management of upper urinary tract calculi with ureteroscopic techniques. This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP.
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Apr 1, Issue. Diagnosis and Initial Management of Kidney Stones. Washington University School of Medicine, St. Louis, Missouri Am Fam Physician.
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